Depends first on the powder coat paint and application qualities. It seems it's too easy nowadays to advertise a paint job as "Powder Coat Tough" or something like that just because it's been powder-coated, it's something valuable or extra special. Well that's true ONLY if the job was performed properly with good materials.I agree, once the powder coat has an opening, the metal is exposed and can rust. This happens with paint as well. Powder coat is worse since it traps moisture underneath the surrounding areas. I do have an old chair-lift seat that I powder coated and have had hanging from a pole on my dock with over 20 years of use now. Still looks new, so it really depends on the "use".
Within one year with my new 5000gvw Load Trail 5x8 hydraulic-dumper trailer the powder coat was saying goodbye. And not even on wear areas. A poor quality PC job can cause more probs than it solves.